The present invention relates to an arrangement for a fuel tank for heavy vehicles.
Fuel tanks for heavy vehicles have special requirements and a special design compared with tanks for passenger cars. The tanks in heavy vehicles often have a volume of several hundred liters, and they can be installed in an entirely unprotected position. Today""s heavy vehicles mainly have tanks made of steel or aluminium. Each in its own way possesses characteristics in respect of which an improvement would have been desirable. This is true, for example, of corrosion, manufacturing efficiency, sensitivity to external influences and weight. Previously disclosed tanks made of steel are prone to rusting, and aluminium tanks can easily buckle and become corrugated. The manufacture of tanks in plastic by the rotational moulding process has started on a limited scale, although these tanks exhibit functional limitations associated with the manufacturing method, which imposes restrictions on their possible sizes and shapes. The difficulty in fitting transverse walls poses problems with bulging long sides. All fuel tanks for heavy road vehicles with a certain internal volume are provided, or should at least be provided with internal baffle plates to reduce the dynamic mass forces during driving. These baffle plates are horizontal in all previously existing applications.
Fuel tanks made of plastic material have assumed a dominant position in the market for passenger cars. These tanks have a smaller volume, and the loading on structural components is thus significantly lower. Because of the limited volume, there is also no need for baffle plates.
It has not been possible to use thermoplastic material for heavy vehicles, due to the lack of material rigidity and the difficulty in fitting the necessary baffle plates. The external wall thicknesses required to obtain sufficient rigidity to carry the load imposed by the fuel are not practicable in production if rational methods are to be used.
Horizontal baffle plates, which are used exclusively today, have a limited effect on mass movements in a transverse direction inside the tank. Slight natural oscillations arise in the liquid inside the tank when driving on uneven roads, which in turn imposes outward and inward pumping loadings on the sides of the tank next to any baffle plates. These are dealt with today by resorting to external straps, which must be positioned solely with regard to this effect and not where it is most rational for the vehicle as a whole, i.e. the attachment points are determined by an overriding factor and cannot be optimized.
The principal object of the present invention is thus, in the first instance, among other things to solve the aforementioned problems by simple and effective means.
The aforementioned object is achieved by means of an arrangement in accordance with the present invention, which is characterized essentially in that a middle section, consisting of plastic or aluminium material with an at least essentially identical transcurrent cross section in the horizontal direction viewed in the longitudinal direction, exhibits internal partitions extending horizontally in the longitudinal direction and bulkheads extending across the aforementioned partitions in the longitudinal direction, in that pairs of end pieces forming end walls exhibit essentially the same profile as the circumference of the middle section and at least parts of the cross section of the partition as end pieces which meet one another and a middle section for welding together at the respective ends of the assembled fuel tank, and in that the partitions of the end pieces exhibit recesses forming connecting paths between the various formed sections in the middle section, in conjunction with which preferably longitudinally extending recesses in the middle section are provided for the purpose of receiving reinforcement and/or for suspending the fuel tank.
A further object of the present invention is to manufacture fuel tanks in accordance with the invention by rational and simple means.
The aforementioned further object is achieved by means of a process in accordance with the present invention, which is characterized essentially in that a partition, which consists of plastic or aluminium material with an at least essentially identical transcurrent cross section in the horizontal direction viewed in the longitudinal direction, and which exhibits internal partitions extending horizontally in the longitudinal direction and bulkheads extending across the aforementioned partitions in the longitudinal direction, is extruded and is then cut to the desired length or is injection moulded, and in that pairs of end pieces forming end walls, which exhibit essentially the same profile as the circumference of the middle section and at least parts of the cross section of the middle section as end pieces which meet one another and a middle section for welding together at the respective ends of the assembled fuel tank, and in that the partitions of the end pieces, which exhibit recesses forming connecting paths between the various formed sections in the middle section are injection moulded and are then welded together with the middle section.